As well known in the art, sealing rings for disposition between relatively moving parts of mechanisms have long been known and used. Such rings have been used, for example, on pistons in cylinders of internal combustion engines, movable shafts in casings, transmissions and the like.
The precise construction of the rings have varied substantially and primarily with respect to the ring ends. Such ring ends have included abutting faces formed ar right angles to the axis of the ring, slanted end faces adapted for interengagement, and various means have been provided on, or proximate, the ring ends to operatively interlock the ends when assembled on a part to prevent its displacement therefrom subsequent to mounting, and also during pre-assembly of a mechanism incorporating a part having such sealing ring.
In some known constructions having interengaging notches in the ring ends and even in types having sloping faces in the notches for interengagement, there have been weakened sections or portions in the ring material below the formed notches or cuts due to removal of ring body material in formation of the notches. An example of this particular type of construction is disclosed in prior British Pat. No. 1,406,375, issued Sept. 17, 1975 to Nippon Piston Ring Co., Ltd. The ring construction shown in this patent has the inherent drawback which can result in breakage or distortion in use due to the weakened area resulting from formation of the notch. It is also difficult in this prior ring construction to provide desired clearance tolerances in application and use. While basically the British patent discloses a split-ring having notches formed in the ends which can be interengaged to prevent the ring from springing open when the ring is inserted in a bore, for example, and contact faces of the locking ends are inclined at an angle from the axis of the ring, the ring disclosed in the patent has disadvantages and defects which delete, either completely, or partially, the effective end use of such a ring. These drawbacks and defects in the prior ring flow primarily from the method of their manufacture and the mechanism or machinery for manufacturing the same.
Initially, it is pointed out that the ring construction shown in the British patent requires a plurality of separate machine operations to form the hooks, and to appropriately trim the ring ends. The method utilized basically includes a plurality of cutters which are sequentially traversed with respect to the ring blank, each separate cutting member, upon movement, serving to form a particular portion of the notch. It will be noted that the base of the notch so formed has an angular or triangularly shaped notch therein intermediate the ends of the base surface. This construction provides a weakened area or section in the finalized ring.
The method wherein the cutters and machining cycle utilized require advancing of plural separate cutting or milling members at different times, in different parts of the cycle, can adversely affect the end clearance variation if the setup is not precisely exact. Under some manufacturing steps used in forming such a construction, it is possible that inertia forces, caused by movement of a carrier utilized in manufacture of the ring, can cause the ring ends to move out of a desired position, and possibly result in additional variation of desired end clearances. It is therefore to be noted that in the final hook configuration of the ring of this British patent, as shown, the end clearance is in actuality larger than required, and this can allow excessive leakage when in an installed, operative position in different mechanisms with which used.
Other configurations of interlocking end rings have incorporated drawbacks wherein angles of mating faces are too steep, or have the angles of interconnection therebetween rounded, and having radii of such dimentions as to allow the rings to become unhooked, causing the rings to break during assembly into cylinders or the like. This drawback primarily is related to a construction wherein the faces of the notch are substantially perpendicular to one another.
It is also known that a multiple number of cutting steps required can result in inaccuracies through wear and misalignment. Manifestly, plural steps also severely effect manufacturing time and, accordingly, costs involved.
Prior known and used types of sealing rings, their methods of manufacture, and apparatus for their production have not been entirely satisfactory in use.
Prior drawbacks and problems are overcome by the concepts involved in the present invention, and particularly in the form where the interengaging and interacting faces of the notches are slanted away from the ring ends. A positive interlock is thereby formed and, as above pointed, out, the material of the ring body has the strength preserved through uniformity of the material section below the notch over the linear extent of the notch base face or surface. The apparatus and system whereby this is accomplished is taught in the present invention.
While the present invention will be specifically described in preferred forms, obviously, minor variations can be incorporated but remaining within the scope of the invention.